Pneumatic tank trucks are in widespread usage for transport of fluent materials, such materials being maintained under pressurized conditions. Pneumatic tank trucks employ one or more openings or hatchways located at the tank top. These openings are covered by a closure or hatch cover which forms a seal with the tank. Conventionally such covers must be opened and closed manually, the truck driver or other individual being required to climb to the top of the truck to perform the required task each and every time the closure must be opened or closed. This is not only time consuming but also dangerous, particularly when the tank top is dirty or slippery. The operation is particularly difficult and dangerous in inclement weather conditions.
As will be seen in greater detail below, the present invention encompasses a closure device which either opens or closes without the driver or another person being required to position himself or herself on the tank top. An inflatable seal is employed to maintain a fluid-tight connection between the closure and the tank top when the closure is closed.
The use of inflatable seals in connection with doors or other closures is known per se and reference may be had to the following United States patents for representative constructions:
U.S. Pat. No. 3,694,962, issued Oct. 3, 1972, U.S. Pat. No. 3,339,785, issued Sep. 5, 1967, U.S. Pat. No. 3,352,446, issued Nov. 14, 1967, U.S. Pat. No. 3,946,772, issued Mar. 30, 1976, U.S. Pat. No. 3,747,275, issued Jul. 24, 1973, U.S. Pat. No. 4,150,509, issued Apr. 24, 1979, U.S. Pat. No. 4,228,135, issued Oct. 14, 1980, U.S. Pat. No. 3,623,627, issued Nov. 30, 1971, and U.S. Pat. No. 5,295,605, issued Mar. 22, 1994.
None of the known prior art arrangements teach or suggest the pneumatic tank truck closure apparatus disclosed and claimed herein.